At the time, getting a sufficiently accurate clock that would keep time though the year meant building a 60kHz MSF ‘Rugby’ receiver (now called a ‘Time from NPL’ receiver as the signal stopped coming from Rugby years ago), or take 1Hz pulses from a GPS receiver and count them.
The first option was too complicated, and the second was too power hungry.
Now it seems the world has changed there are some lovely inexpensive little modules that will do the MSF reception for you.
These seem to be built around a few different ICs, with the micro-power chips from Finland-based Micro Analog Systems looking particularly nice.
Micro Analog Systems does its own modules, but these are not showing up in stock anywhere I look. However Amazon has one branded Canaduino and made by Universal-Solder that is based on a Micro Analog Systems MAS6180C (photo and diagram).
It comes with a pre-wound ferrite rod antenna for about a tenner, and the related Universal-Solder web page has lots of useful onward information links.
This can run from voltages between 2 and 15V, and consumes under 100µA provided that the on-board leds are disabled (there is a jumper for disabling them). BTW – the leds only work with at least 3V applied and, BTW2 – the on-board micro-power regulator is an ME6209 from MicrOne.
I am guessing here, but an MCU running off a 32kHz watch crystal could probably do all the necessary monitoring and processing, and could even disable the receiver for much of the day. It could even run of a 32kHz RC oscillator, calibrate its own frequency error from the receiver (maybe with a temperature measurement too) and just wake up the receiver a few minutes befor noon each day to get an accurate noon ‘tick’.
Hats off to all concerned.
The two images on this web page are copied from the Universal Solder web page here. Please get in touch if they have been used inappropriately and they will be removed immediately.
I’ve had hours of endless fun playing with MSF receivers.
Some of them even worked.
Though one that went by the name of Rewbichron never did no matter what I did with it.
Irritatingly enough it was the one I paid actual money for.
I found another example in the junkroom at work: that one didn’t work either.
Sorry zeitghost, I missed your comment.
My receiver, I am ashamed to say, is still in its anti-static bag awaiting experimentation.
Still, I expect to have some spare time at last soon – who knows what will get made 🙂